The present invention relates to a gear tester for controlling the position of mating gears, such as hypoid or spiral beveled gears to verify the quality of a given gear set under fixed and known mounting conditions to determine sensitivity of the gears to various programmed misalignments, changes in mounting conditions and the like which simulate deflections during use.
In the prior art, it has long been the practice to test on a substantially 100% basis, spiral bevel and hypoid gears to determine running qualities, such as tooth-bearing contact. It has further been known to use machines for running sets of bevel or hypoid gears together to determine optimum running positions of one gear relative to another. Such a device is shown in U.S. Pat. No. 3,795,143. The device in this patent permits adjusting the axes of the pinion and gear relative to each other for the offset of axes, as well as the positioning of the degree of intersection of the gear. However, this procedure involves the use of large slides and manual controls for the final positioning.
In order to determine the effect of various tolerances or differences in gear and pinion positions, the need has existed for accurately controlling the position of the gear in several degrees of freedom, while determining loads in the gear as well as simultaneously determining other performance factors of the gears. Such performance factors may be noise, the "footprint" of the pinion on the gear, and deflection that might occur on the gear itself caused by loading on the gear. Thus, measuring the loads on the gear and the controlled degrees of freedom is beneficial in determining factors that may be necessary for housing designs to minimize deflections and alignment problems. Finally, in matched sets of gears, an optimum running position of a pinion and the gear can be determined and used for final adjustment when assembled in a housing for use so that other than the nominal axial offset and positioning of the gears can occur.
Four degrees of freedom are usually needed for providing alignment between a stationary pinion and a pinion spindle and the gear and the gear spindle. My co-pending application entitled CONTROLLABLE GEAR TESTING SYSTEM, filed on the same day as the present application, discloses a gear testing system with up to four degrees of freedom for positioning the gear relative to a fixed stationary pinion. Specifically, this system permits controlling movement of the gear along the gear rotational axis, which position is essentially the gear mounting distance that determines the backlash ("Q"); controlling the shaft angle ("S"), which is the angle of the axis of the gear shaft or spindle relative to the axis of rotation of the pinion; controlling the hypoid or spiral bevel offset, which is the offset of the pinion axis from the gear axis in the plane passing through the gear axis and parallel to the spindle rotational axis, commonly called a vertical position ("V"); and the position of the gear axis along the pinion axis, which is commonly called the pinion axial position ("H") and can generally be referred relative to a reference plane perpendicular to the pinion spindle axis, generally the plane surface supporting the back surface of the pinion. The terminology for horizontal and vertical positions are traditional references used in describing relative pinion and gear positions and are not intended to be limitations of the present invention.